CVE-2026-72209 (GCVE-0-2026-72209)
Vulnerability from cvelistv5
Published
2026-08-15 05:54
Modified
2026-08-17 05:41
Severity ?
VLAI Severity ?
EPSS score ?
Summary
In the Linux kernel, the following vulnerability has been resolved:
ntfs: validate attribute values on lookup
ntfs_attr_find() and ntfs_external_attr_find() check that generic
resident attribute values fit in their attribute records and that
fixed-size resident values are large enough. For variable-length resident
formats, however, the fixed part is not enough: embedded length fields
can still point callers past the resident value.
A crafted image can set a small resident $FILE_NAME value_length while
leaving file_name_length large. Callers then trust file_name_length and
read past the resident value when converting or comparing the name. This
was reproduced with a crafted image under KASAN as a slab-out-of-bounds
read from the kmalloc-1k MFT record copy. The stack included
ntfs_lookup(), ntfs_iget(), ntfs_read_locked_inode(), ntfs_attr_name_get(),
ntfs_ucstonls(), and utf16s_to_utf8s().
Add a shared attribute value validator and use it before a lookup path
can return an attribute, including the AT_UNUSED enumeration case where
callers inspect returned attributes directly. The helper validates
resident value bounds, minimum resident value sizes, variable-length
$FILE_NAME fields, and non-resident mapping-pairs metadata that was
previously checked separately in both lookup paths.
This also preserves the intended resident @val matching semantics in the
external attribute lookup path. The old duplicated validation block
overwrote the actual resident value length with the type-specific minimum
length before comparing @val, so variable-length resident values could
fail to match even when the bytes were identical. Keep the comparison on
the actual value length, and make ntfs_attrlist_entry_add() compare
resident attributes with lowest_vcn zero instead of reading the
non-resident union member after a successful resident match.
Reject non-resident $FILE_NAME records too: the format requires
$FILE_NAME to be resident and callers treat returned records as resident.
References
Impacted products
{
"containers": {
"cna": {
"affected": [
{
"defaultStatus": "unaffected",
"product": "Linux",
"programFiles": [
"fs/ntfs/attrib.c",
"fs/ntfs/attrlist.c"
],
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"versions": [
{
"lessThan": "e4c36dfac57a7261e9aeb0f3a7f30944a8aefb56",
"status": "affected",
"version": "6ceb4cc81ef3409ff79dcb959771f9110787397a",
"versionType": "git"
},
{
"lessThan": "d5803e3345dae9c6470bb61869885236276b9a35",
"status": "affected",
"version": "6ceb4cc81ef3409ff79dcb959771f9110787397a",
"versionType": "git"
}
]
},
{
"defaultStatus": "affected",
"product": "Linux",
"programFiles": [
"fs/ntfs/attrib.c",
"fs/ntfs/attrlist.c"
],
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"versions": [
{
"status": "affected",
"version": "7.1"
},
{
"lessThan": "7.1",
"status": "unaffected",
"version": "0",
"versionType": "semver"
},
{
"lessThanOrEqual": "7.1.*",
"status": "unaffected",
"version": "7.1.5",
"versionType": "semver"
},
{
"lessThanOrEqual": "*",
"status": "unaffected",
"version": "7.2",
"versionType": "original_commit_for_fix"
}
]
}
],
"cpeApplicability": [
{
"nodes": [
{
"cpeMatch": [
{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"versionEndExcluding": "7.1.5",
"versionStartIncluding": "7.1",
"vulnerable": true
},
{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"versionEndExcluding": "7.2",
"versionStartIncluding": "7.1",
"vulnerable": true
}
],
"negate": false,
"operator": "OR"
}
]
}
],
"descriptions": [
{
"lang": "en",
"value": "In the Linux kernel, the following vulnerability has been resolved:\n\nntfs: validate attribute values on lookup\n\nntfs_attr_find() and ntfs_external_attr_find() check that generic\nresident attribute values fit in their attribute records and that\nfixed-size resident values are large enough. For variable-length resident\nformats, however, the fixed part is not enough: embedded length fields\ncan still point callers past the resident value.\n\nA crafted image can set a small resident $FILE_NAME value_length while\nleaving file_name_length large. Callers then trust file_name_length and\nread past the resident value when converting or comparing the name. This\nwas reproduced with a crafted image under KASAN as a slab-out-of-bounds\nread from the kmalloc-1k MFT record copy. The stack included\nntfs_lookup(), ntfs_iget(), ntfs_read_locked_inode(), ntfs_attr_name_get(),\nntfs_ucstonls(), and utf16s_to_utf8s().\n\nAdd a shared attribute value validator and use it before a lookup path\ncan return an attribute, including the AT_UNUSED enumeration case where\ncallers inspect returned attributes directly. The helper validates\nresident value bounds, minimum resident value sizes, variable-length\n$FILE_NAME fields, and non-resident mapping-pairs metadata that was\npreviously checked separately in both lookup paths.\n\nThis also preserves the intended resident @val matching semantics in the\nexternal attribute lookup path. The old duplicated validation block\noverwrote the actual resident value length with the type-specific minimum\nlength before comparing @val, so variable-length resident values could\nfail to match even when the bytes were identical. Keep the comparison on\nthe actual value length, and make ntfs_attrlist_entry_add() compare\nresident attributes with lowest_vcn zero instead of reading the\nnon-resident union member after a successful resident match.\n\nReject non-resident $FILE_NAME records too: the format requires\n$FILE_NAME to be resident and callers treat returned records as resident."
}
],
"metrics": [
{
"cvssV3_1": {
"baseScore": 9.8,
"baseSeverity": "CRITICAL",
"vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H",
"version": "3.1"
},
"scenarios": [
{
"lang": "en",
"value": "AV:N - NTFS registers ntfs_export_ops; remote nfsd/ksmbd VFS lookups on an exported crafted NTFS volume reach ntfs_lookup\u2192ntfs_iget\u2192ntfs_read_locked_inode\u2192ntfs_attr_name_get without local syscall access.\nAC:L - The attacker fully controls on-disk $FILE_NAME metadata (small resident value_length with large file_name_length) in a crafted image; the fix commit reproduced the slab OOB read via ntfs_lookup deterministically with no races.\nPR:N - Triggering needs only read access to mounted NTFS content (e.g., authenticated or guest NFS/SMB client on an exported share) or supplying removable media later mounted by the host; no init-namespace root or CAP_SYS_ADMIN on the lookup path.\nUI:N - Once a crafted NTFS volume is mounted and exported (or loop-mounted in a user namespace), normal remote lookups/opens reach the vulnerable attribute parsing without further victim clicks or cooperative actions.\nS:U - The slab out-of-bounds read and potential kernel crash stay within the mounting host kernel authority; this is standard filesystem parsing exploitation, not a VM escape, IOMMU bypass, or cross-sandbox scope change.\nC:H - Callers trust inflated file_name_length and ntfs_ucstonls/utf16s_to_utf8s read past the resident $FILE_NAME value in the kmalloc-1k MFT record copy, disclosing adjacent slab heap memory beyond a few bytes.\nI:H - Attacker-controlled file_name_length drives kernel parsing of forged resident metadata and adjacent slab contents; per kernel CNA guidance, this memory-corruption class can be leveraged for arbitrary kernel modification or control-flow hijack beyond the immediate read.\nA:H - KASAN reports slab-out-of-bounds read from the MFT record copy on lookup; reading past the resident $FILE_NAME value can oops or panic the kernel when accessing invalid adjacent memory."
}
]
}
],
"providerMetadata": {
"dateUpdated": "2026-08-17T05:41:36.117Z",
"orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"shortName": "Linux"
},
"references": [
{
"url": "https://git.kernel.org/stable/c/e4c36dfac57a7261e9aeb0f3a7f30944a8aefb56"
},
{
"url": "https://git.kernel.org/stable/c/d5803e3345dae9c6470bb61869885236276b9a35"
}
],
"title": "ntfs: validate attribute values on lookup",
"x_generator": {
"engine": "bippy-1.2.0"
}
}
},
"cveMetadata": {
"assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"assignerShortName": "Linux",
"cveId": "CVE-2026-72209",
"datePublished": "2026-08-15T05:54:04.772Z",
"dateReserved": "2026-08-09T03:40:39.912Z",
"dateUpdated": "2026-08-17T05:41:36.117Z",
"state": "PUBLISHED"
},
"dataType": "CVE_RECORD",
"dataVersion": "5.2"
}
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Sightings
| Author | Source | Type | Date |
|---|
Nomenclature
- Seen: The vulnerability was mentioned, discussed, or seen somewhere by the user.
- Confirmed: The vulnerability is confirmed from an analyst perspective.
- Published Proof of Concept: A public proof of concept is available for this vulnerability.
- Exploited: This vulnerability was exploited and seen by the user reporting the sighting.
- Patched: This vulnerability was successfully patched by the user reporting the sighting.
- Not exploited: This vulnerability was not exploited or seen by the user reporting the sighting.
- Not confirmed: The user expresses doubt about the veracity of the vulnerability.
- Not patched: This vulnerability was not successfully patched by the user reporting the sighting.
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